WhatsApp Audio call bug causing black screen/dim screen

Well, I have been having issues with my 950XL for last few months now.

Sometimes after waking up the phone, the display would remain blank for 5-6 seconds, but the iris scanner would turn on and unlock the phone after which the display would come back on, as if nothing happened. Sometimes it would work as usual, sometimes the display would remain painfully dim till you lock/unlock next. This problem would persist till you rebooted the phone.

Today I found out exactly what the problem was, WhatsApp Voice calls. The problem is easily reproducible.

Call someone on Whatsapp, hang up. Lock the screen, unlock it. At this point, the screen would refuse to turn on straight away. Reboot the phone, problem gone till next Whatapp voice call. I can reproduce this 100% of the time.

Unfortunately the problem exists with both Whatsapp and Whatsapp beta, both the latest release preview/production and fast ring builds, so there's no work around, other than to avoid WhatsApp voice calls.

Can other try this and chime in? I am more interested in whether this is a 950XL only problem or affects other phones, too.

Same here, on my 950. Another bug I noticed with latest production WhatsApp is long delay after navigating back to the app (from Translator or another app). Screen is black for a few seconds, an eternity in 2016.